Cygnus X-1 revisited

Liang, Edison; Nolan, P. L.

doi:10.1007/bf00176834

Cited by 123 publications

(85 citation statements)

References 107 publications

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“…The soft (< 10 keV) X-ray luminosity of Cyg X-1 is ∼ 8.5 × 10 36 erg/s on average [5], while during the heao-3 γ 1 , γ 2 states it was even lower [10]. Taking into account that for hard X-ray photons the Comptonization efficiency in the hot plasma drops substantially [21] while the number of photons decreases as well, the obtained values, L soft ≈ 10 37 erg/s, match the data.…”

Section: Resultsmentioning

confidence: 99%

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A model for the high-energy emission of Cyg X-1

Moskalenko¹,

Collmar²,

Schöenfelder³

1997

AIP Conference Proceedings

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Abstract. We construct a model of Cyg X-1 which describes self-consistently its emission from soft X-rays to MeV γ-rays. Instead of a compact pair-dominated γ-ray emitting region, we consider a hot optically thin and spatially extended proton-dominated cloud surrounding the whole accretion disc. The γ-ray emission is due to bremsstrahlung, Comptonization, and positron annihilation, while the corona-disc model is retained for the X-ray emission. We show that the Cyg X-1 spectrum accumulated by osse, batse, and comptel in 1991-95, as well as the heao-3 γ 1 and γ 2 spectra can be well fitted by our model (see [1] for details). The derived parameters are in qualitative agreement with the picture in which the spectral changes are governed by the mass flow rate in the accretion disc. In this context, the hot outer corona could be treated as the advection-dominated flow co-existing with a standard thin accretion disc.

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Section: Resultsmentioning

confidence: 99%

“…There are occasional periods of 'high' state emission. Remarkable is c 1997 American Institute of Physics 1 the anticorrelation between the soft and hard X-ray components [5], which is clearly seen during transitions between the two states. Since its launch in 1991 cgro has observed Cyg X-1 several times.…”

Section: Introductionmentioning

confidence: 99%

A model for the high-energy emission of Cyg X-1

Moskalenko¹,

Collmar²,

Schöenfelder³

1997

AIP Conference Proceedings

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“…Support for this suspicion is found on detailed analyses carried on radial velocity measurements as well as on recent analyses based on spectrum synthesis (Herrero et al 1995) both of which give a mass of about 10 M 0 , comfortably larger than the 3 M 0 upper limit of a neutron star mass. The luminosity is sub-Eddington, but greater than 0.01 L Edd (Liang and Nolan 1984). Cygnus X-1, being one of the most studied sources in the sky, especially in the hard X-rays, some of its properties (characteristic hard X-ray spectrum, episodic emergence of an ultra soft component, anticorrelated soft and hard X-ray transitions, chaotic variability down to milliseconds, persistent gamma-ray tail above an MeV, episodic gamma-ray bumps at a few hundred keV-MeV, persistent radio emission and radio flaring correlated with X-ray transitions and Low-Frequency Quasi Periodic Oscillations (QPO)) have been accepted as evidence for black hole candidacy (Liang 1998).…”

Section: Observational Aspects: a Brief Reviewmentioning

confidence: 86%

Pion production In The Inner Disk Around Cygnus X-1

Filho¹

2004

AIP Conference Proceedings

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Neutron production via4 He breakup and p(p, nπ + )p is considered in the innermost region of an accretion disk surrounding a Kerr Black Hole. These reactions occur in a plasma in Wien equilibrium, where (radiatively produced) pair production equals annihilation. Cooling of the disk is assumed to be due to unsaturated inverse Comptonization of external soft photons and to the energy needed to ignite both nuclear reactions. Assuming matter composition of 90% Hydrogen and 10% He, it is shown that, close to the border of this region, neutron production is essentially from 4 He breakup. Close to the horizon, the contribution from p (p, nπ + ) p to the neutron production is comparable to that from the breakup. It is shown that the viscosity generated by the collisions of the accreting matter with the neutrons, may drive stationary accretion, for accretion rates below a critical value. In this case, solution to the disk equations is double-valued and for both solutions protons overnumber the pairs. It is claimed that these solutions may mimic the states of high and low luminosity observed in Cygnus X-1 and related sources. This would be explained either by the coupling of thermal instability to the peculiar behavior of the viscosity parameter α with the ion temperature that may intermittently switch accretion off or by the impossibility of a perfect tuning for both thermal and pair equilibrium in the disk, a fact that forces the system to undergo a kind of limit cycle behavior around the upper solution.

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“…One of the most interesting sources is 1E 1740.7−2942, the brightest and hardest persistent X-ray source within a few degrees of the GC. Because of a similar hard X-ray spectrum and comparable luminosity to Cygnus X-1 (Liang & Nolan 1984), 1E 1740.7−2942 is classified as a black hole candidate. Because of the two-sided radio jets associated to the source, the object was dubbed the first "microquasar" (Mirabel et al 1992), an X-ray binary whose behavior mimics quasars on a much smaller scale.…”

Section: Scientific Objectivesmentioning

confidence: 99%

The protoMIRAX hard X-ray imaging balloon experiment

Braga

D'Amico

Ávila

et al. 2015

A&A

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Context. The protoMIRAX hard X-ray imaging telescope is a balloon-borne experiment developed as a pathfinder for the MIRAX satellite mission. The experiment consists essentially in a coded-aperture hard X-ray (30-200 keV) imager with a square array (13 × 13) of 2 mm-thick planar CZT detectors with a total area of 169 cm 2 . The total, fully-coded field-of-view is 21 • × 21 • and the angular resolution is 1 • 43 . Aims. The main objective of protoMIRAX is to carry out imaging spectroscopy of selected bright sources to demonstrate the performance of a prototype of the MIRAX hard X-ray imager. In this paper we describe the protoMIRAX instrument and all the subsystems of its balloon gondola, and we show simulated results of the instrument performance. Methods. Detailed background and imaging simulations were performed for protoMIRAX balloon flights. The 3σ sensitivity for the 30-200 keV range is ∼1.9 × 10 −5 photons cm −2 s −1 for an integration time of 8 h at an atmospheric depth of 2.7 g cm −2 and an average zenith angle of 30 • . We developed an attitude-control system for the balloon gondola and new data handling and ground systems that also include prototypes for the MIRAX satellite.Results. We present the results of Monte Carlo simulations of the camera response at balloon altitudes, showing the expected background level and the detailed sensitivity of protoMIRAX. We also present the results of imaging simulations of the Crab region. Conclusions. The results show that protoMIRAX is capable of making spectral and imaging observations of bright hard X-ray source fields. Furthermore, the balloon observations will carry out very important tests and demonstrations of MIRAX hardware and software in a near space environment.

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Cygnus X-1 revisited

Cited by 123 publications

References 107 publications

A model for the high-energy emission of Cyg X-1

A model for the high-energy emission of Cyg X-1

Pion production In The Inner Disk Around Cygnus X-1

The protoMIRAX hard X-ray imaging balloon experiment

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